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Constructing quantum many-body scars from weak Hilbert space fragmentation

Fan Yang, Matteo Magoni, and Hannes Pichler

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Phys. Rev. B 113, 174307 – Published 18 May, 2026

DOI: https://doi.org/10.1103/cpt2-kqdy

Abstract

Quantum many-body scars (QMBS) are exotic many-body states that exhibit anomalous nonthermal behavior in an otherwise ergodic system. In this work, we demonstrate a simple, scalable, and intuitive construction of QMBS in a kinetically constrained quantum model exhibiting weak Hilbert space fragmentation. We show that exact QMBS can be constructed by injecting a quasiparticle that partially activates the frozen regions in the lattice. Meanwhile, the inelastic collision between multiple quasiparticles allows for the construction of approximate scars, whose damping is governed by an emergent two-body loss. Our findings establish direct connections between quantum many-body scarring and Hilbert space fragmentation, paving the way for systematically constructing exact and approximate QMBS with nontrivial spatial connectivity. The proposed model can be readily implemented in neutral-atom quantum simulators aided by strong Rydberg interactions.

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Phys. Rev. B 113, 174307– Published 18 May, 2026
  • Received 10 July 2025
  • Revised 3 March 2026
  • Accepted 10 April 2026
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